"The Environmental Protection Agency, facing intense opposition from Congressional Republicans and industry over a broad range of new air quality regulations, said Monday that it was delaying by two months the release of a proposed rule on greenhouse gas emissions from power plants and other major pollution sources.

The delay of the rule, which will have a major impact on the nation's efforts to reduce emissions of gases blamed for the warming of the planet, is the latest step by the E.P.A. to slow the issuing of regulations that its critics claim will hurt economic growth, drive up energy costs and cut employment. The delay is a tacit admission that the regulations pose difficult political, economic and technical challenges that cannot be addressed on the aggressive timetable the agency set for itself early in the Obama administration.

The agency said it was pushing back the new greenhouse gas proposal to the end of September to allow more time to consider input from power companies, environmental advocates and others. Officials said they still expected to have a final rule in place by May 2012."